#include <stdio.h>
#include <math.h>
int main()
{
    double m = 0;
    double n = 0;
    while (scanf_s("%lf%lf", &m, &n) != EOF)
    {
        double sum = m;
        while (n > 1)
        {
            sum += sqrt(m);
            m = sqrt(m);
            n--;
        }
        printf("%.2lf\n", sum);
    }
    return 0;
}